I'm talking about a real screw chuck, not the one that comes with a scroll chuck. My experience with a screw chuck goes way back, long before 4-jaw chucks or even the screw chucks of today were available I had to make my own. I'd seen the shopmade ones the professional Myrtlewood woodturners on the Oregon coast were using, so I copied theirs. A faceplate, a block of wood, some epoxy and a shortened lag bolt did the trick. Today I use a Glaser, a big improvement over my shopmade chuck. There are some good screw chucks on the market at half the price of a Glaser
For a long time I attached the screw chuck directly to the blank. A wood plug in the bottom of the bowl was much better than dealing with faceplate screw holes as just about everybody did in those days. The wood plug was acceptable then. Richard Raffan even has a photo of the bottom of one of my pieces with a plug in his early book on form.
Most turners in the early days who used a glue block inserted some paper between the blank and the glue block. Made it easier to remove the glue block. I found that messy and had one or two flying bowls because it came off too easy. So then I started just parting the block off. I still do that today.
I use glue blocks on most of my pieces. I like the fact that it separates the vessel from the faceplate, screw chuck or 4-jaw chuck. Gives me more room to work...for example when I'm doing a fully beaded piece, with beads clear to the bottom. If I'm turning a shallow piece there's no room for a tenon. I do my finishing in a different way than most turners. I do it while the piece is still mounted on the glue block and on the lathe. Works great for applying the finish and for polishing. After the finish is completed I part the piece off and reverse it to do the bottom. The glue block allows me to do that. I much prefer finishing that way and recommend it. When I was teaching, my students all did it that way and many still do.
I find the screw chuck easy to use and IMO is a more secure way to fasten than a chuck. I do however own several 4-jaw chucks and use them, often with a tenon cut on the glue block. If I use a glue block on an endgrain vessel I cut a small tenon on the blank and bore a corresponding hole in the glue block with a forstner bit. I use a faceplate if the piece is tall. Otherwise I cut a tenon and use a chuck. Most secure way of fastening is the faceplate.. I don't trust an end grain glue joint. A tip...Most screw chucks come with a 3/4 inch screw. I grind mine off to 5/8 inch. The hold is just as good and the hole in the glue block isn't as deep. Another...When applying a finish the piece comes on and off the screw chuck several times. I use a 1/4 inch plywood insert so that that there aren't as many screw threads. Easier on and off. Couple of spins of my nine inch handwheel.
In the photo I'm using a chuck with a glue block. When the finish is done I'll part it off at the glue line. In case you're wondering why the headstock is backwards, I do my hollowing in reverse on the outboard side of my lathe
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